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Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 5648
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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My furnace will not shut off and the display says the temp

Customer Question

My furnace will not shut off and the display says the temp is 07!!! I just got home and it has to be over a 100 degrees in here.
Submitted: 1 year ago.
Category: HVAC
Expert:  airheatman replied 1 year ago.

Lest start by pulling front off of thermostat and see if heat will go off.

Customer: replied 1 year ago.
I turned it in the off position already, so it is off
Customer: replied 1 year ago.
The display flashes between the time and temp... Time is correct, temp says
Customer: replied 1 year ago.
07
Expert:  airheatman replied 1 year ago.

Ok remove batteries and install them backwards for about 5 seconds.The re install correctly Se if that resets thermostat.

Customer: replied 1 year ago.
okay, hold on
Customer: replied 1 year ago.
UMM, OMG, THAT MADE IT START SMOKING
Expert:  airheatman replied 1 year ago.

Remove them and put them back correctly. Should not have started smoking. Thermostat most likely has an internal short.

Customer: replied 1 year ago.
I am a girl, and that just scared me, I don't dare put them back in
Expert:  airheatman replied 1 year ago.

I understand. Most likely the thermostat has taken a power spike and the little computer board has a short. This is why heat did not shut down and display was incorrect. You will need to get another thermostat. I will be happy to recommend a replacement and guide you through installing if you want to do yourself.

Customer: replied 1 year ago.
I am going to attach 2 pics... one wire looks strange to me. I put an arrow on pic
Expert:  airheatman replied 1 year ago.

Standing by for pictures

Customer: replied 1 year ago.
i don't know why they won't send
Customer: replied 1 year ago.
now they did, lol
Expert:  airheatman replied 1 year ago.

Give me a moment to look them over

Customer: replied 1 year ago.
No problem!!!
Expert:  airheatman replied 1 year ago.

That orange looking wire may just be unused and tucked back into wall. Wires sort of block letters. Tell me where each goes, For example red to R, White to W etc.

Customer: replied 1 year ago.
I'm referring to the one that looks like it's wrapped or something, and has white freys sticking out
Customer: replied 1 year ago.
what appears to be frayed ends
(circled)
Expert:  airheatman replied 1 year ago.

That is not an issue those frays are just moisture wicking threads to absorb and moisture that might get in the sheathing

Customer: replied 1 year ago.
W white
RH red and orange
B empty
RC orange
Expert:  airheatman replied 1 year ago.

Ok and on bottom terminals?

Customer: replied 1 year ago.
C blue
G green
O empty
Y yellow
Expert:  airheatman replied 1 year ago.

OK excellent Now I think your thermostat may have taken a surge or a spike. Can you get the numbers to do correctly with batteries out?

Customer: replied 1 year ago.
The time is correct, temp is 06
Expert:  airheatman replied 1 year ago.

Lets try this. Press Up arrow Down arrow and Time all at the same time and see if it might reset

Customer: replied 1 year ago.
I tried that once, do you want me to try again?
(batteries are still out)
Customer: replied 1 year ago.
Tried again, it did not work
Expert:  airheatman replied 1 year ago.

I you have already tried and the battery backwards made it smoke, there is most likely a short in the board.Is there anywhere like Lowes or Home Depot still open where you might pick up a new thermostat?

Customer: replied 1 year ago.
there is a Lowe's but they closed at 9p
Expert:  airheatman replied 1 year ago.

So anything still open,. Even Walmart should have one

Customer: replied 1 year ago.
I could go there. Do I have to turn off elec to unit somehow before putting in? Cuz I'm not so sure I know how to do that.
Expert:  airheatman replied 1 year ago.

It is best so you don't risk shorting anything. There should be a breaker by unit inside. Otherwise just be careful not to let the blue wire touch any other wire while changing it.

Customer: replied 1 year ago.
A breaker by the thermostat? Or in the circuit box thingy? (lol)
Expert:  airheatman replied 1 year ago.

No breaker or disconnect will be by the furnace .As long as we don't let blue touch anything we can leave power on

Expert:  airheatman replied 1 year ago.

If you are going to get a thermostat I will wait up for you so we can get this fixed tonight.Just let me know.

Customer: replied 1 year ago.
Okay, I can go up there, but it will take me like 45 mins round trip. Will you be on in the morning? Can I request you somehow and go to the store and install it then?
Expert:  airheatman replied 1 year ago.

Yes I will be here tomorrow .If that works best for you, that is fine.Just sign in to JustAnswer and go to MY Questions and that will bring you here.

Customer: replied 1 year ago.
Oh, okay. Then I will do that. It's plenty HOT in here, so I think I will be fine until morning!
Expert:  airheatman replied 1 year ago.

Excellent .Talk to you then